A solar panel's operating point (voltage and current) is decided by an electronic circuit called a maximum power point tracker (“MPPT”). As the temperature increases, the MPPT drifts to produce a lower energy output. The VOC, or open circuit voltage, reduces significantly and ISC, or short circuit current, increases marginally.
FIG. 5 is a circuit equivalent of a conventional solar cell. RSH represents the junction resistance of the cell.
Currently, MPPT based solar systems do not provide for temperature compensation. Thus, when panel temperature increases, the VOC drops, and the panel works at new VMPP and IMPP values. There is no correction provided for reducing panel stress.